Learnings from the "Web Development 301 - Typed Functional Programming" course as part of the Coronasafe Engineering Fellowship 2021

Begin by running npm install.

You are expected to write the code in src/todo.res file.

This file will get compiled into src/todo.bs.js file automatically by the VSCode rescript extension. However, this way you won't be able to see the compiler errors clearly. So for this, run npm run start in a Terminal.

Once you are done with the changes you should be able to execute the todo app by running the following command from the terminal.

On Windows:

.\todo.bat

On *nix:

./todo.sh

These scripts execute the compiled src/todo.bs.js file using node.

Try running tests.

Now run npm test and you will see all the tests failing. As you fill in each functionality, you can re-run the tests to see them passing one by one.

Specification

1. The app can be run in the console with ./todo.

2. The app should read from and write to a todo.txt text file. Each todo item occupies a single line in this file. Here is an example file that has 2 todo items.

water the plants
change light bulb

3. When a todo item is completed, it should be removed from todo.txt and instead added to the done.txt text file. This file has a different format:

   x 2020-06-12 the text contents of the todo item

   1. the letter x
   2. the current date (UTC/GMT) in yyyy-mm-dd format
   3. the original text

   The date when the todo is marked as completed is recorded in the yyyy-mm-dd format (ISO 8601). For example, a date like 15th August, 2020 is represented as 2020-08-15.

4. The application must open the files todo.txt and done.txt from where the app is run, and not where the app is located. For example, if we invoke the app like this:

   $ cd /path/to/plans
   $ /path/to/apps/todo ls
   

   The application should look for the text files in /path/to/plans, since that is the user’s current directory.

Usage

1. Help

Executing the command without any arguments, or with a single argument help prints the CLI usage.

$ ./todo help
Usage :-
$ ./todo add "todo item"  # Add a new todo
$ ./todo ls               # Show remaining todos
$ ./todo del NUMBER       # Delete a todo
$ ./todo done NUMBER      # Complete a todo
$ ./todo help             # Show usage
$ ./todo report           # Statistics

2. List all pending todos

Use the ls command to see all the todos that are not yet complete. The most recently added todo should be displayed first.

$ ./todo ls
[2] change light bulb
[1] water the plants

3. Add a new todo

Use the add command. The text of the todo item should be enclosed within double quotes (otherwise only the first word is considered as the todo text, and the remaining words are treated as different arguments).

$ ./todo add "the thing i need to do"
Added todo: "the thing i need to do"

4. Delete a todo item

Use the del command to remove a todo item by its number.

$ ./todo del 3
Deleted todo #3

Attempting to delete a non-existent todo item should display an error message.

$ ./todo del 5
Error: todo #5 does not exist. Nothing deleted.

5. Mark a todo item as completed

Use the done command to mark a todo item as completed by its number.

$ ./todo done 1
Marked todo #1 as done.

Attempting to mark a non-existed todo item as completed will display an error message.

$ ./todo done 5
Error: todo #5 does not exist.

6. Generate a report

Use the report command to see the latest tally of pending and completed todos.

$ ./todo report
yyyy-mm-dd Pending : 1 Completed : 4